I’m trying to understand what’s happening in this circuit:

I------------------T1 (+333V)
I                 I
I                 R1(10K)
(pos)             I
1000V             I------------gnd (0V)
(neg)             I
I                 R2(10K)
I                 I
I                 IT2(-333V)
I                 I
I                 R3(10K)
I                 I
I-----------------IT3 (-666.7V)

I am learning basic DC theory from reading and sometimes I come across something I’d like to ask a question about, so:

  1. In the above circuit, without the ground, the voltage across all components would begin at 10V and finish at 0V. By adding a ground, I’m basically saying “here is 0V” and everything gets redefined in reference to that point and I end up with a 10 volt circuit with +3.33 as it’s highest voltage and -6.667 as it’s lowest.

  2. The electrons could care less, they still flow from the anode to the cathode of the battery under normal conditions, going from the highest potential to the lowest.

  3. This example was only used to demonstrate voltage dividers. It revolved around worker protection present in aluminum processing. Each machine is in series and mobile grounds are used nearest the machine a worker is using. I assume that this allows the worker to have the least exposure to electrical shock as they are also at ground potential?

I actually think working though these questions has cleared everything up, but please, comment on anything I got wrong.

Also, sorry about the crappy drawing, the autowrap in this editor really made things tough to format

Thanks!

  • @MotoAshEnglish
    4•11 months ago

    DISCLAIMER: Not an electrician or other sparky, I just like to have fun with electronics.

    “Ground” is only 0v by convention. What it literally is, is, “What ever general voltage potential everything around the circuit has that the circuit could short to.” Most circuits aren’t going to short over air, and any separate circuit can drift in its relative voltage levels to other circuits, so it’s a problem that is dealt with via extra circuitry like a physical ground connection 99.9% of the time.

    The entire point of grounding is to both make sure the circuit doesn’t float off to some crazy voltage level that could end up literally sparking to other things, and also to provide an alternate path for electricity if something is wrong with the circuit (like an electrician just introduced their hand to the circuit). To provide that alternate path, ground MUST be at a lower potential than the power source (by convention, since we could have made +v = 0 and shift the whole values appropriately). Relativity is the name of the game.

    The aluminum machinery could simply be an older design where both sides of the AC get used as-is, or grounded straight to chassis, or any other number of poor practices which would then require an operator to have their own ground connection to not get the everloving shit shocked out of them for simply touching the controls.

    If a metal chassis or metal controls are any part of the circuit, you will have to do something to factor in people touching stuff. Ungrounded or un-looped (not completing the circuit across themselves but simply touching a live circuit) people can still be shocked even on DC circuits because an ungrounded person still acts like a capacitor. A grounded person is simply a resistor instead, but that can easily be the difference between life and death.